Malignant transformation rate of oral leukoplakia in the past 20 years: A systematic review and meta-analysis.

This meta-analysis aimed to assess the rate of malignant transformation (MT) of oral leukoplakia (OL) and to study potential risk factors for the MT of OL into oral squamous cell carcinoma (OSCC). We performed a bibliographic search on nine electronic databases, including PubMed, MEDLINE, and Wanfang Data, for data on the MT rate of OL. Possible risk factors were calculated using Comprehensive Meta-Analysis and Open Meta [Analyst] software. The pooled proportion of OL MT for the total population described in the 26 selected studies was 7.20% (95% confidence interval: 5.40-9.10%). Nonhomogeneous type lesions, higher grades of dysplasia, the location of the lesion (tongue and multifocal), and female sex had significant effects on the MT of OL. OL tended to develop into OSCC (7.2%), and those with significant MT risk factors should be subjected to regular follow-up and observation. However, we require large-scale prospective studies to validate these results, together with unified clinicopathological diagnostic criteria, standardized risk factor recording/assessment methods, and long-term follow-up guidelines.

Guan JY ，Luo YH ，Lin YY ，Wu ZY ，Ye JY ，Xie SM ，Li J ... -  《-》

Malignant transformation of oral leukoplakia: Systematic review and meta-analysis of the last 5 years.

Oral leukoplakia (OL) is the most frequently encountered oral potentially malignant disorder. The aims of this systematic review are to estimate the overall malignant transformation of OL and to assess the risk factors associated with malignant transformation of OL published in the last 5 years (2015-2020). We performed a bibliographic search in PubMed, Scopus, Web of Science, Embase, and Cochrane databases with keywords "oral leukoplakia", "oral cancer", "oral carcinoma" and "oral squamous cell carcinoma". Meta-analysis was conducted using a random-effects model. Twenty-four studies were selected, that reported a total of 16,604 patients. Malignant transformation proportion varied between 1.1% and 40.8%. Female gender, non-homogeneous clinical type, and presence of epithelial dysplasia were significantly related to MT. Other risk factors previously suggested did not show significant results. The pooled proportion of malignant transformation MT was 9.8% (95% CI: 7.9-11.7). It is necessary to continue to conduct well-designed prospective clinicopathological studies on OL, using a uniform definition for OL to reduce the risk of bias for evaluating various factors associated with the MT.

Aguirre-Urizar JM ，Lafuente-Ibáñez de Mendoza I ，Warnakulasuriya S 《-》

Risk assessment of malignant transformation of oral leukoplakia in patients with previous oral squamous cell carcinoma.

The aim of this study was to identify the risk factors associated with developing oral squamous cell carcinoma (OSCC) from surgically excised oral leukoplakia (OL) in patients with previous oral cavity cancer. Clinicopathological data of 84 patients who were treated for OL between July 2002 and July 2020 and who had previously received treatment for OSCC were reviewed retrospectively. The follow-up time ranged from 0.69 to 17.99 years (mean 6.78 ± 4.25 years). The overall cumulative malignant transformation rate was 25% and the annual transformation rate was 5.73%. Kaplan-Meier survival analysis and the log-rank test showed that Candida infection (P = 0.010) was a risk factor associated with malignant transformation. In the multivariate Cox regression analysis, tongue and floor of the mouth as the location of the leukoplakia (P = 0.039), multifocal lesions of OL (P = 0.047), and Candida infection (P = 0.018) were the three independent prognostic factors related to the development of OSCC from the treated OL. A cautious approach to OL of the tongue with Candida infection or multifocal disease in this group of patients would be appropriate.

Yang SW ，Lee YC ，Lee YS ，Chang LC ，Lai YR ... -  《-》

Annual malignant transformation rate of oral leukoplakia remains consistent: A long-term follow-up study.

Numerous clinical and histopathological characteristics have been associated with malignant transformation (MT) of oral leukoplakia (OL), including classic and differentiated epithelial dysplasia, but MT predictions remain suboptimal. The objective of this study was to determine the annual MT rate of OL and to identify clinicopathological risk factors associated with MT. 170 patients with OL were included in this retrospective cohort study, 117 females and 53 males. Follow-up ranged from 12 to 219 months (median 54). The analyzed variables included age, gender, smoking habits, clinical presentation, subsite, size and treatment. In a subgroup of 140 patients, histopathological diagnoses were reviewed with regard to the presence of dysplasia, discerning both classic dysplasia and differentiated dysplasia. MT occurred in 23% of the patients, resulting in an annual MT rate of 4.9% (95% CI: 3.5 - 6.6) which remained consistent. High-risk subsite (tongue and floor of mouth) was the only clinical predictor for MT (Hazard Ratio = 2.7, 95% CI: 1.3 - 5.5, p = 0.007). In 140 patients, classic dysplasia (Hazard Ratio = 7.2, 95% CI: 1.6 - 33.1, p = 0.012) and differentiated dysplasia (Hazard Ratio = 6.6, 95% CI: 1.2 - 25.4, p = 0.026) were predictors for MT. Binary grading between dysplasia and no dysplasia was significant for predicting MT (Hazard Ratio = 6.4, 95% CI: 1.5 - 27.5, p = 0.013). Since annual MT rate of OL remains stable during follow-up, regular long-term or even life-long follow-up is advocated. Specific oral subsites and epithelial dysplasia are predictors for MT of OL.

Evren I ，Brouns ER ，Wils LJ ，Poell JB ，Peeters CFW ，Brakenhoff RH ，Bloemena E ，de Visscher JGAM ... -  《-》

The combination of SMAD4 expression and histological grade of dysplasia is a better predictor for the malignant transformation of oral leukoplakia.

Xia RH ，Song XM ，Wang XJ ，Li J ，Mao L ... -  《PLoS One》